I found another explanation:
PS: I create Jira - [MP1-5031] Fix Invalid File Handle in Setup - MediaPortal JiraCause: A font is being used and cannot be installed. In newer versions ignore the error (since this also means that the font is already available) and simply continue with the installation. The issue may be resolved by restarting windows and loading the font installers from our website. Otherwise you can manually delete our fonts and restart windows.